In the prior art, it is known to produce preparations by blending substances in a vat and introducing powdered particles into the vat in order to incorporate them in the blend.
Such preparations are commonly produced for pharmaceutical, cosmetic or agri-food industry applications. For pharmaceutical or cosmetic applications, the incorporated particles can in particular form the active ingredient of the composition and must then be incorporated into the blend in very precise proportions.
In order to produce these preparations, blender assemblies are known. According to the most widespread technology, these include a vat, kept in depression and intended to receive the blend, a rotor including blending blades and engaging with motor means in order to be rotated, and a stator including an annular ring surrounding the rotor and having radial orifices for the passage of the blend radially projected by said rotor.
Two methods are commonly used to incorporate the particles into the preparation.
According to a first method, illustrated in FIG. 1, the particles are introduced by suction into the vat kept in depression via an admission duct opening into the bottom of the vat, laterally to the rotor-stator unit. The admission duct is equipped with a gate making it possible to control the introduction of particles into the vat. The particles to be incorporated in the blend circulate in the vat approximately following the path of the arrows f1. However, in this case, the introduction flow of the powder is directly related to the level of vacuum in the vat. Also, for a given gate, it is necessary to increase the vacuum to increase the flow of particles introduced. However, depending on the viscosity of the blend in the vat, an excessively high vacuum level causes too fast a passage of the particles through the blend and the suctioned particles stick against the upper portion of the vat; this creates cleaning and loss-of-product problems.
According to a second method, illustrated in FIG. 2, the blender assembly is equipped with an outside hose allowing a recirculation of the preparation. In this embodiment, the powder particles are introduced into the vat via an admission duct opening into the outside hose. However, this method poses problems in terms of cleaning the outside recirculation hose. Furthermore, the introduction flow of the powder is limited by the dimensions of the outside hose and by the circulation flow therein.